Elongated guiding members are widely used in medical procedures. A common example are the guidewires used to locate intravascular devices such as angioplasty catheters. Since guidewires must traverse the peripheral and tortuous coronary in order to reach the desired treatment location, they must exhibit a number of important characteristics. Specifically, a guidewire should have sufficient strength and elasticity to impart suitable pushability, trackability, torqueability, flexibility and handleability.
It has proven challenging to maximize these functional characteristics while maintaining the necessary overall dimensions. One prior art guidewire design utilizes a proximal hypotube portion. Although this design offers advantages, it also suffers from certain drawbacks. Most significantly, the use of a hypotube increases the chance the guidewire will kink as it is being advanced within the vasculature or through a guiding catheter. In addition, due to the reduced cross sectional area relative to a solid wire of the same outer diameter, such hypotube guidewires generally suffer from similarly reduced torqueability.
Thus, there is a need for an elongated guiding member with a proximal hypotube portion having improved performance characteristics. Specifically, there is a need for a hypotube guidewire with enhanced pushability that reduces the chance of kinking. There is also a need for a guidewire with a proximal hypotube shaft that transmits torque more efficiently than conventional guidewires formed from a hypotube. This invention satisfies these and other needs.
The invention is directed to an elongated guiding member for medical devices such as a guidewire having an elongated proximal hypotube portion with an internal insert disposed within the interior hypotube and a relatively short solid core distal portion. The insert may be composed of metals such as stainless steel, shape memory/superelastic materials such as nickel-titanium alloys, composite materials or polymeric materials. Preferably, the solid distal core portion has a swaged or plunge ground proximal end that may be inserted into the distal end of the proximal hypotube portion. The proximal and distal core portions are secured by mechanical means or by adhesive, solder, brazing, welding or other suitable means. The proximal hypotube portion of the guiding members of the invention preferably are provide with a low friction coating.